Packard Forum Index » V-8 (1955-56)

Yes Eric. If fluid is supposed to pass thru the 'relief port' then why would the gasket be made to seal it off????

pics:

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BTV Compensator

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I believe the original minor kit includes only the following parts for rebuilding the hydraulic master cylinder:

* cover gasket
* piston cup (rubber)
* piston oil seal (leather)
* vacuum shell gasket
* vacuum shell seal
* vacuum shell end plate gasket
* compensator port valve
* compensator port valve seal
* output fitting seal
* residual check valve/seal

The factory parts books shows same P/Ns for all of these parts between 52-54 & 55-56 EXCEPT for the residual check valve. That one item may be what accounts for the two different numbers for minor kits. While the repro kits that I've used had a different style (flat, disc type) of residual check valve than what came out of the BTVs in my '56 cars, it fit and worked fine.

Although the parts book shows that the compensator port valve is serviced as an assembly, the minor kit includes the valve stem with seal. I've never had a problem with the port valve fitting, but - again - have seen corroded and broken springs.

On a related note, the fill plug gasket (Gr 1.337) (like the compensator prot valve spring) was never included in the minor kits. Because that gasket has been missing from every car I ever inspected, I made replacements from some poly sheet stock. However, I've heard some people talk about a large copper annular gasket (crush washer).

There has got to be something else going on between the units and that port function.

Max Merritt has illustrations of what appears to be NOS kits. The one for 52-4 is identical to the one I have and has not got the hole. The one he shows for 55-6 is the same as what is in the aftermarket kit with the hole to nowhere.

Either we are both wrong as to the function of the port and it was discontinued or there has to be a hole or some kind of relief in the cover for it to be functional which appears to not be the case.

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You tell me, here's pics of my original BTV unit off of my '56 Pat parts car, untouched since Ike was in office:

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Altho pics can be decieving based on resolution of my computer it appears that BOTH of the MM NOS kits show a compensator valve stem that more closely resembles stem in Kevin AZ's pic of the aftermarket kit. Note that it appears rather flat on the bottom instead of hemispherical like my alleged OEM compenstator stem.

NOTE that the factory schematics show something that more closely resembles my alleged oem stem that what is in the dealer kits as shown by the dealers.

Also, a pic of the master cylinder itself, which obviously had fluid in it at one time or another:

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I am starting to wonder if they bought complete units or bought by the piece and lids from the earlier years were installed. Sure would be nice if someone had access to another car which used that unit. Chev, Cad to see if there is a difference.

Here's a pic of the compensator valve:

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